In a small bowl, whisk together 1 teaspoon egg replacer with 2 tablespoons water & set aside.
In the bowl of a mixer fitted with the paddle attachment, cream together butter and sugar until fluffy for approx. 2 mins. Add egg replacer mixture and vanilla extract, mix for 1 minute.
Into another bowl sift together flour, cocoa, bi-carb soda and salt. Mix the dry ingredients into the wet and gently fold together.
Into the dough, add chocolate chips, marshmallows, crushed nuts and coconut, fold to combine.
Scoop and roll the dough into 20 equal balls. Place dough balls onto a tray and into the fridge to chill for 30 minutes. Preheat oven to 180ºC (fan forced).
Place dough balls onto a tray lined with baking paper at least 5cm apart and bake 12 minutes or until the cookie edges are slightly set.
As soon as the cookies come out of the oven, top them with the extra marshmallows and chocolate chips. Carefully press them into the surface of the cookie before they cool down.
Allow the cookies to cool for 10 minutes on the baking tray before carefully transferring to a wire rack to cool completely.